In known intake apparatus of the kind referred to above, the potentiometer and the full-load stop device must be adjusted within pregiven tight tolerances for a so-called full-load point. A full-load point is defined as a signal of pregiven value from a potentiometer which indicates that the throttle flap has reached its full-load position.
It is assumed that the full-load point is theoretically then reached when the throttle flap is displaced so far that the throttle flap lies parallel to the intake pipe axis. This angle is referred to in the following as a displacement angle of 90.degree. or as a parallel position angle. The presence of this angle is determined in that the potentiometer connected to the throttle flap shaft supplies a signal which indicates a pregiven voltage-divider value, for example, the value 0.1. The permissible voltage-divider value range lies typically between 0.95 (throttle flap closed which corresponds to idle) and 0.05 (when the throttle flap is rotated beyond the parallel position angle until a stop is reached). The displacement range of the throttle flap of approximately 90.degree. corresponds approximately to a voltage-divider ratio value range of 90/100. Therefore, a relatively good correspondence exists between a change of the voltage-divider ratio of 0.01 and a change of the displacement angle of the throttle flap of 1.degree..
In known intake apparatus, the tolerance for the voltage-divider values is given typically as approximately 0.01 for the overall value range from idle to full load, however, greater tolerances are occasionally permitted in the mid and higher load ranges. The pregiven tolerance for the potentiometer corresponds to a corresponding tolerance angle of approximately 1.degree. which is in accordance with the foregoing.
When adjusting the intake apparatus, the procedure which is typically followed is that first the throttle flap is closed completely and the potentiometer is so far rotated with respect to the throttle flap shaft (or the potentiometer slider is so displaced) that a voltage-divider ratio of 0.94 is adjusted based on the output signal from the potentiometer. The throttle flap is then rotated to the extent that the voltage-divider ratio value of 0.01 results with this ratio value being provided for the parallel position angle. Because of the tolerance given in the foregoing, the angle in unfavorable conditions can actually be 89.degree. or 91.degree.. The throttle flap should come into contact engagement at the full-load stop device at a displacement angle of 91.degree. at the earliest in order to ensure, for all cases, that the voltage-divider ratio of at least 0.01 is reached. The adjustment tolerance for this stop device is typically pregiven with approximately .ltoreq..+-.2.degree.. Overall, this means that the throttle flap can be brought against the stop between 91.degree. and 95.degree. displacement angle.
The above tolerances were up to now the conventional tolerances and were measured so tightly that, as a rule, an adjustable resistor was necessarily used for maintaining the potentiometer tolerance and, to maintain the tolerance for the stop device, the stop device was made adjustable or must be worked on.
It is presently known to construct apparatus so that reliable characteristics are obtained notwithstanding the expansion of tolerances. This general task was also present in connection with the intake apparatus according to the invention described herein.